A lens is, but without limitation, a piece of glass or other transparent substance with curved or flat surfaces for concentrating and/or dispersing light rays. A lens may be convex or concave. Lenses are typically used in eyeglasses, visors, cameras, microscopes, and telescopes, etc. Lenses and devices utilizing a lens or lenses are tested for optical quality to ensure they are within required specifications. Optical quality includes prism, spherical, and cylindrical power. Prism describes the phenomena that moves an object in any direction other than where it should appear in real space. Refractive powers are spherical and cylindrical. Spherical power makes an object appear larger or smaller than what it should appear in real space i.e., reading glasses are positive spherical powered lenses. Cylindrical power makes an object elongated into a cylinder shape.
Currently a lensometer is used to analyze and test lenses and devices utilizing a lens. Many devices under test by the Department of Navy are physically too large or oddly shaped to properly fit in a lensometer. Additionally, lensometers cannot adequately test the combined optical power of stacked lenses or multiple substrates of lenses, like a pair of spectacles placed behind a visor. Lensometers cannot physically or optically accommodate testing through multiple substrates or differentiate the power attributed to each substrate. Lensometers cannot analyze a series of lenses.